Laser performance

The 10 long-pulse (LP) beams each provides up to 500 joules of ultraviolet light (351 nanometres) in a pulse that is 1 nanosecond in duration. These are arranged in two cones of five beams, at 50 degrees to the axis of the target chamber and have f/4 focussing optics. Nominal spot size in 100 micrometres although kinoform phase plates are available, allowing spots with a flat-top spatial profile and 300-micron diameter to be used. Each cone can be fired independently of the other, allowing single-sided drive, and the energy and timing of the LP beams can be individually controlled.

Pulses widths of 100 picoseconds to 5 nanoseconds, in 100 picoseconds increments, with a highly versatile pulse shaping capability and there can be up to a 10 nanosecond delay between the individual long-pulse beamlines. The delay between the long-pulse and short-pulse beamlines can be changed to arbitrarily high values (>1 microsecond).

Focal spot smoothing options are available on all of the beamlines with 1 or 2D Smoothing by Spectral Dispersion (SSD) in conjunction with phase plates deployed prior to the final focussing lenses.

The two short-pulse (SP) petawatt beams use chirped-pulse amplification (CPA) to produce 500 joules of infrared light (1053 nanometres) in pulses that are 0.5 picoseconds long. The two CPA beams are delivered orthogonally to target and can be used for heating or backlighting.

Currently, one of the short-pulse beamlines has the option of being converted to the second harmonic (527 nanometres) at 300 mm aperture and provides up to 100 joules with a significantly reduced pre-pulse. Further development work, to reduce the pre-pulse present in the infrared, is planned.

The short-pulse beamlines can also provide conventional backlighting, with standard long-pulse shaping and pulse length options in the third harmonic (approximately one day of work is required to change from one mode of operation to the other).

There is also the option of providing two synchronised ~50 millijoules, 400 femtoseconds, probe beams in the fourth harmonic (263 nanometres) for optical diagnoses of the target interaction.